Rear connection means for molded case circuit breaker

ABSTRACT

Mounting means for front connecting a relatively large molded case circuit breaker in a switchboard includes a frame having roller means for temporary support of the breaker while it is being mechanically and electrically secured in operative position. The frame mounts a pair of molded insulating blocks, each having a plurality of bus units secured thereto and permanently connected to the buswork of the switchboard. Inserts extending through the blocks provide stud means to secure the frame to structural members of the switchboard, and these same inserts provide thread formations cooperating with bolt means that mechanically secure the breaker. Additional inserts in the blocks in cooperation with bolt and partially loaded spring means are used for securing the bus units to the frame in a floating like manner, permitting self-adjustment as electrical connections are being made to the circuit breaker. In one embodiment of this invention, electrical connections are made by utilizing tulip type plug-in connectors in a staggered arrangement to utilize available depth in the switchboard and conserve scarce space outboard of the circuit breaker top, bottom, and sides. Lever means mounted to the frame and engageable with the circuit breaker facilitates moving the relatively heavy circuit breaker and overcoming the relatively large friction forces resulting from the electrical plug-in connectors.

United States Patent [191 Gryctko et al.

[ Apr. 23, 1974 1 REAR CONNECTION MEANS FOR MOLDED CASE CIRCUIT BREAKER [75] Inventors: Carl E. Gryctko, Haddon Heights;

Albert Strobel, Cherry Hill, both of NJ.

[73] Assignee: I-T-E Imperial Corporation,

Philadelphia, Pa. 22 Filed: July 27, 1972 [21] Appl. No.: 275,624

[52] US. Cl 317/120, 339/64 M, 317/101 CB [51] Int. Cl. H02b 1/20 .[58] Field of Search 317/112, 118-120, 317/101 CB; 339/64 R, 64 M, 259 R [56] References Cited UNITED STATES PATENTS 2,930,020 3/1960 Powell 339/64 M 3,488,623 l/1970 Stephenson 339/64 M 3,562,593 2/1971 Bould 317/112 3,474,206 10/1969 Gryctko 317/119 2,480,059 8/1949 Stickney t. 339/192 T 2,789,024 4/1957 l-leisler 317/101 CB 3,710,199 l/l973 Cignoni, Jr. 317/101 CB Primary Examiner-James R. Scott Assistant ExaminerGerald P. Tolin Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb & Soffen.

[5 7] ABSTRACT Mounting means for front connecting a relatively large molded case circuit breaker in a switchboard includes a frame having roller means for temporary support of the breaker while it is being mechanically and electrically secured in operative position. The frame mounts a pair of molded insulating blocks, each having a plurality of bus units secured thereto and permanently connected to the buswork of the switchboard. Inserts extending through the blocks provide stud means to secure the frame to structural members of the switchboard, and these same inserts provide thread formations cooperating with bolt means that mechanically secure the breaker. Additional inserts in the blocks in cooperation with bolt and partially loaded spring means are used for securing the bus units to the frame in a floating like manner, permitting self-adjustment as electrical connections are being made to the circuit breaker.

In one embodiment of this invention, electrical connections are made by utilizing tulip type plug-in connectors in a staggered arrangement to utilize available depth in the switchboard and conserve scarce space outboard of the circuit breaker top, bottom, and sides. Lever means mounted to the frame and engageable with the circuit breaker facilitates moving the relatively heavy circuit breaker and overcoming the relatively large friction forces resulting from the electrical plug-in connectors.

6 Claims, 12 Drawing Figures PATENTEBAPR 23 1974 SHEET 3 UF 8 FTP.-

-ww rm ww k PATENTED I974 SHEET 6 [IF 8 PMEMED APR 2 3 1974 SHEET 7 [IF 8 REAR CONNECTION MEANS FOR MOLDED CASE CIRCUIT BREAKER This invention relates to high current capacity molded case circuit breakers and more particularly relates to novel means for mounting this type of circuit breaker in a switchboard.

Multipole molded case circuit breakers are presently being constructed with continuous current ratings in excess of 2,000 amperes. Even though the circuit breakers are relatively compact, the large current carrying parts and the large moldings bring the weight of the unit up to a point where handling becomes cumbersome. This leads to difficulty in mounting the circuit breaker in a switchboard, especially when bus connections must be made at the rear of the breaker.

To overcome these difficulties, the instant invention provides a frame that is mounted in the switchboard to serve as a means for temporarily supporting the circuit breaker during the time it is being electrically and mechanically connected to the switchboard. The frame also supports a rear connection unit that is installed in the field prior to installation of the circuit breaker. All switchboard bus and/or cable connections are made to the rear connections unit before the circuit breaker is installed, and none of these connections need be disturbed in order to install or remove the circuit breaker. Further, the electrical connections between the circuit breaker and the rear connection unit are all made from the front of the circuit breaker.

The rear connection unit is provided with two molded mounting blocks, each supporting a plurality of bus units, one for each pole of the circuit breaker. Inserts molded into the mounting blocks facilitate connection of the mounting block to the frame and facilitate connection of the frame to structural members of the switchboard. The same inserts that are used for connection of the frame to the structural members of the switchboard are used for mechanical securement of the circuit breaker, so that the assembly is made rigid and is capable of safely withstanding short-circuit stresses at the rear connection conductors. Inserts that mount the bus units to the block also mount partially loaded resilient members and are constructed so that the bus units are normally positioned by the resilient members, yet the bus units are free to move during the making of electrical connection, in order to compensate for a degree of misalignment.

To further facilitate mounting of the breaker, the mounting frame is provided with rollers that engage the bottom end of the circuit breaker to mechanically support the latter as it is being moved into operative position and as mechanical and electrical connections are being made between the circuit breaker and switchboard. A lever may be provided to move the circuit breaker after the latter is supported on the rollers of the frame. This lever is especially useful when plug-in type electrical connections are utilized between the circuit breaker terminals and the bus units of the rear connection unit. In accordance with the instant invention, electrical connections may be made by utilizing a plurality of tulip connectors for each terminal of the circuit breaker. These connectors are arranged in rows, and the multileaved, garter spring surrounded, portions of adjacent tulip connectors are mounted in different planes, thereby utilizing available rear space and conserving scarce vertical and horizontal spaces.

Accordingly, a primary object of the instant invention is to provide novel means for mounting a large molded case circuit breaker in a switchboard.

Another object is to provide a rear connection unit in which the bus units are mounted for limited movement to compensate for misalignment.

Still another object is to provide novel means for rigidifying the mechanical connections between a molded case circuit breaker and structural members of a switchboard.

A further object is to provide novel means for temporarily supporting a circuit breaker in a switchboard during and prior to mechanically and electrically connecting the circuit breaker in the switchboard.

A still further object is to provide a novel arrangement of tulip type electrical connectors.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a front elevation of a circuit breaker supported by a mounting means constructed in accordance with teachings of the instant invention.

FIG. 2 is a side elevation, looking in the direction of arrows 22 of FIG. 1.

FIG. 3 is a front elevation of the mounting frame and busing elements.

FIG. 4 is a plan view, looking in the direction of arrows 44 of FIG. 3.

FIG. 5 is a rear perspective of the mounting means.

FIG. 6 is an enlarged view, partially sectioned, showing securement of one of the mounting blocks to the mounting frame.

FIG. 7 is a cross-section taken through line 7--7 of FIG. 3, looking in the direction of arrows 7-7.

FIG. 8 is a cross-section taken through line 8-8 of FIG. 1, looking in the direction of arrows 8-8.

FIG. 9 is a side elevation of a circuit breaker, partially sectioned, to illustrate another embodiment of this invention in which tulip connectors are utilized.

FIG. 10 is a plan view of one of the mounting blocks of FIG. 9, looking in the direction of arrows 10-10 of FIG. 9.

FIG. 1 1 is a front elevation of a mounting frame having a lever to facilitate moving the circuit breaker.

FIG. 12 is a side elevation looking in the direction of arrows 12--12 of FIG. 11.

Now referring to the figures. Rear connection mounting means for supporting molded case circuit breaker 25 in a switchboard (not shown) includes generally U- shaped sheet metal frame 31 having rear wall 32 and side walls 33, 34. Three horizontal rods 35, 36, 37 are connected opposite ends thereof to sidewalls 33, 34 to rigidify frame 31. Each of the rods 35-37 is of reduced diameter at the ends thereof to rotatably mount bushings 38 which engage the lower end of circuit breaker 25 to temporarily support the latter during connection to the switchboard.

Frame 31 supports two molded insulating blocks 41, 42 that are disposed within respective rectangular cutouts 43, 44 in rear wall 32. Each block 41, 42 is provided with four inserts that include stud portions 45, 46, 47, 48 extending through clearance apertures in rear wall 32 of frame 31 for securement of blocks 41, 42 to frame 31. The inboard studs 47, 48 are engaged by nuts 51, 52 respectively to provide direct securement to rear wall 32. The outboard studs 45, 46, after passing through rear wall 32, pass through vertical legs of upper and lower horizontal angle irons 55, 56 and are engaged by nuts 53, 54 to mechanically secure blocks 41, 42 to frame 31 and secure frame 31 to angle irons 55, 56. The latter are structural members of the switchboard (not shown). Bolts 58, located between cutouts 43, 44, extend through rear wall 32 of frame 31, through the web of horizontal channel 59 and are engaged by nuts 61 to further mechanically secure frame 31 to the switchboard, channel 59 being another structural member of the switchboard.

As seen in FIG. 7, the forward portion 62 of insert 65 containing stud 46, includes interanlly threaded axial recess 63 which receives the thread of circuit breaker mounting bolt 64. The head of bolt 64 is disposed within recess 66 in base 26 of circuit breaker 25, so as to be accessible when circuit breaker housing cover 27 is removed. Insert 67, containing stud 47, is of the same construction as insert 65. Thus, it is seen that there are rigid metal connections securing circuit breaker 25 to switchboard structural members 55, 56.

Bus units 71, 72, 73 are secured to upper insulator 41, and additional bus units 74, 75, 76 are secured to lower insulator 42. Since each of the bus units 71-76 is of identical construction and the mounting thereof to its insulator block is the same, a description of only unit 71 appears hereinafter, with particular reference to FIGS. 4 and 6.

But unit 71 includes slab-like block 79 having a plurality of parallel spaced bus bars 81-84 brazed to the rear thereof and extending through and to the rear of rear chamber 80 in insulator 41. Bus bars 8184 are connected to the busing of the switchboard. A pair of adapter brackets 85, 86 are secured to bus bars 81-84 by bolts 87 and nuts 88, with bolts 87 also passing through bus bars spacers 89. The ends of adapters 85, 86 are provided with cars 91, extending parallel to the plane of rear wall 32 of frame 31. Normally, each car 91 bears against the forward surface of an insert 92 molded into and protruding from insulator 41.

Insert 92 includes a body portion 94 extending forward of insulator 41 and a threaded recess which receives bolt 93. This projecting body portion 94 extends through adapter ear 91 and mounts bigger lock washer 95. Flat washer 97 abuts the forward end of insert body portion 94, and smaller lock washer 96 is interposed between flat washer 97 and the head of bolt 93. Washer 95 is much stronger than washer 96, and washer 95 is partially loaded only to the extent necessary to normally maintain ear 91 seated against the forward surface of insert 92. This partial loading of lock washer 95 permits bus unit 71 to be tilted and/or pulled forward slightly during the making of electrical connections to circuit breaker 25, as required to compensate for misalignment.

Four threaded recesses 99 in block 79, extending rearward from the forward surface thereof, receive individual bolts 95 which extend through clearance apertures in line terminal 96 of circuit breaker 25 at a portion thereof positioned above are chute 97. Thus, substantial portions of the line terminal rear surface and the block front surface are clamped together to provide a good electrical connection. The heads of bolts 95' are within circuit breaker housing chamber 98, so as to be accessible for front connection merely by removing auxiliary cover 27 a that partially underlies cover 27 and is secured thereto by screws 27b. Similar front connections are made at the other line terminals of circuit breaker 25 and at the load terminals thereof that are accessible by removing the lower auxiliary cover 270 secured to cover 27 by screws 27d.

Now referring to FIGS. 9 and 10, which show an embodiment of the instant invention in which connections between the circuit breaker terminals and the terminals or bus units of the rear connection mounting means are of the plug-in type. More particularly, three relatively long studs constituting male connector parts 101, 102, 103 and three relatively short studs 104, 105, 106 extend forward from block 107 of bus unit 108. Studs 101-106 are arranged in two vertical rows, each having three studs, with one row containing long stud 101 interposed between short studs 104, and the other row containing short stud 106 interposed between long studs 102, 103. With this arrangement each long stud 101-103 is adjacent to either two or three of the short studs 104-106, but is not adjacent to another long stud.

Each of the short studs 104-106 near the forward end thereof is provided with an annular recess to facilitate retention of circularly arranged tulip connector fingers or segments constituting female connector parts 110 that are secured by rear garter spring 111. Forward garter spring 112 provides contact pressure between fingers 110 and the three relatively long studs constituting male connector parts 121 that extend rearward from circuit breaker line terminal 122 in alignment with short studs 104-106.

Line terminal 122 also contains three rear projecting short studs 123 in alignment with long studs 101-103. Each of the short studs 123 mounts a set of tulip fingers constituting female connector parts 124 secured by forward garter spring 125 and mounting rear garter spring 126 that provides contact pressure between fingers 124 and long stud 101-103.

With this arrangement it is seen that adjacent studs are too close together to permit mounting of tulip connectors in the same plane on adjacent studs. Thus, the tulip connectors are disposed in forward and rearward planes, and in this manner available front and back space is utilized and scarce horizontal and vertical spaces are conserved.

In the embodiment of FIGS. 11 and 12, pivots 201, 202 secure arms 203, 204 of U-shaped lever member 205 to the respective sidewalls 33, 34 of frame 31, with web 206 of member 205 passing beneath frame 31. Each of the arms 203, 204 constitutes a lever having inwardly extending pins 208 positioned above pivots 201, 202 in close proximity thereto.

In conjunction with lever member 205, the embodiment of FIGS. 11 and 12 utilizes U-shaped bracket 210 having a web extending along the rear surface of circuit breaker 25 and having forwardly projecting arms extending partway along the sides of circuit breaker 25. Bolts 211, extending into inserts in the circuit breaker base and through the web portion of member 210, fixedly secure member 210 to circuit breaker 25. The arms of member 210, along their lower edges, are pro vided with slots 212 to receive pin 208, thereby constituting the connection between lever member 205 in circuit breaker 25. The arms of bracket 210 are also provided with outwardly extending studs 214 having hook receiving annular recesses.

For the mounting of circuit breaker 25, lever memher 205 is pivoted counterclockwise with respect to FIG. 12, and hooks 215 engaging studs 214 are utilized in conjunction with a lifting device (not shown) to position circuit breaker so it is supported on bushings 38, with lever pins 208 disposed within slots 212 of bracket 210. Hooks 215 are disengaged from studs 214, and lever member 205 is then pivoted clockwise (with respect to FIG. 12) about aligned pivot pins 201, 202, to move circuit breaker 25 to its solid line mounting position of FIG. 12. Since pins 208 are so close to pivots 201, 202 and the distances between pivots 201, 202 and the ends of arms 203, 204 are so great, huge mechanical advantages are obtained for moving the heavy circuit breaker 25 to position for mechanical and electrical securement. It is intended that lever 205 and bracket 210 of FIGS. 11 and 12 be used primarily when plug-in electrical connections are utilized, in that the many strong springs providing contact pressure are relatively strong and produce high friction forces.

For those features of construction in circuit breaker 25 that have not been described in detail herein, reference is made to one or more of the copending applications Ser. Nos. 275,568, 275,577, 275,446, 275,578, 275,507, 275,454, 275,508, 275,621, 275,623, 275,569, 275,522, 275,521, 275,523, and 275,622, herewith, and all assigned to the assignee of the instant invention.

Although there has been described a preferred embodiment of this novel invention, many variations and modifications will now become apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. Mounting means for connecting a circuit breaker in switchboard; said mounting means including a frame, insulating mounting block means, fastening means rigidly securing said mounting block means to said frame, a plurality of bus units, and additional fastening means securing said bus units to said mounting block means; said additional fastening means including partially loaded spring means exerting stabilizing forces between said mounting block means and said bus units and permitting independent limited movement for each of said bus units relative to said mounting block means during electrical connection of circuit breaker line and load terminals to said bus units; said additional fastening means also including an internally threaded insert in said mounting block means extending to a forward surface thereof, a bolt threadedly received by said insert with a body portion of said bolt extending forward of said insert. Said spring means being mounted to said body portion; adapter means interposed between said bus units and said mounting block means; said adapter means having an ear portion with an aperture through which the body portion of said bolt extends and said spring means biasing said ear portion toward said forward surface of said mounting block means.

2. The mounting means of claim 1 wherein said frame, at the bottom thereof, including a plurality of tranverse stiffening members; roller members on said stiffening members at opposite ends thereof positioned so as to be beneath and to temporarily support a circuit breaker by engaging the lower end of its housing prior to mechanical securement of such circuit breaker.

3. Mounting means as set forth in claim 2 in which the frame includes a rear wall, side walls extending forward from the sides of said rear wall, and an open front; said stiffening members extending between said side walls and generally parallel to said rear wall.

4. Mounting means as set forth in claim 3 in which the insulating block means is secure to the rear wall of the frame; each of said bus units including a bus block and bus connecting means at the rear of said bus block extending rearward of said rear wall and said mounting block means.

5. Mounting means for connecting a circuit breaker in a switchboard; said mounting means including a frame, insulating mounting block means, fastening means rigidly securing said mounting block means to said frame; said fastening means including a plurality of insert members mounted to said mounting block means; each of said insert members including a stud portion extending to the rear of said mounting block means for securing said frame to a structural element of a switchboard and an internally threaded first portion enterable from the front of said mounting block means by bolt means mechanically securing a circuit breaker supported by said frame; a plurality of bus units, and additional fastening means securing said bus units to said mounting block means; said additional fastening means including partially loaded spring means exerting stabilizing forces between said mounting block means and said bus unit and permitting independent limited movement for each of said bus units relative to said mounting block means during electrical connection of circuit breaker line and load terminals to said bus units.

6. Mounting means as set forth in claim 5 in which said additional fastening means also includes an internally threaded insert in said mounting block means extending to a forward surface thereof, a bolt threadably received by said insert with a body portion of said bolt extending forward of said insert; said spring means being mounted to said body portion; adapter means interposed between said bus units and said mounting block means; said adapter means having an ear portion with an aperture through which the body portion of said bolt extends and said spring means biasing said ear portion toward said forward surface of said mounting block means. 

1. Mounting means for connecting a circuit breaker in switchboard; said mounting means including a frame, insulating mounting block means, fastening means rigidly securing said mounting block means to said frame, a plurality of bus units, and additional fastening means securing said bus units to said mounting block means; said additional fastening means including partially loaded spring means exerting stabilizing forces between said mounting block means and said bus units and permitting independent limited movement for each of said bus units relative to said mounting block means during electrical connection of circuit breaker line and load terminals to said bus units; said additional fastening means also including an internally threaded insert in said mounting block means extending to a forward surface thereof, a bolt threadedly received by said insert with a body portion of said bolt extending forward of said insert. Said spring means being mounted to said body portion; adapter means interposed between said bus units and said mounting block means; said adapter means having an ear portion with an aperture through which the body portion of said bolt extends and said spring means biasing said ear portion toward said forward surface of said mounting block means.
 2. The mounting means of claim 1 wherein said frame, at the bottom thereof, including a plurality of tranverse stiffening members; roller members on said stiffening members at opposite ends thereof positioned so as to be beneath and to temporarily support a circuit breaker by engaging the lower end of its housing prior to mechanical securement of such circuit breaker.
 3. Mounting means as set forth in claim 2 in which the frame includes a rear wall, side walls extending forward from the sides of said rear wall, and an open front; said stiffening members extending between said side walls and generally parallel to said rear wall.
 4. Mounting means as set forth in claim 3 in which the insulating block means is secure to the rear wall of the frame; each of said bus units including a bus block and bus connecting means at the rear of said bus block extending rearward of said rear wall and said mounting block means.
 5. Mounting means for connecting a circuit breaker in a switchboard; said mounting means including a frame, insulating mounting block means, fastening means rigidly securing said mounting bLock means to said frame; said fastening means including a plurality of insert members mounted to said mounting block means; each of said insert members including a stud portion extending to the rear of said mounting block means for securing said frame to a structural element of a switchboard and an internally threaded first portion enterable from the front of said mounting block means by bolt means mechanically securing a circuit breaker supported by said frame; a plurality of bus units, and additional fastening means securing said bus units to said mounting block means; said additional fastening means including partially loaded spring means exerting stabilizing forces between said mounting block means and said bus unit and permitting independent limited movement for each of said bus units relative to said mounting block means during electrical connection of circuit breaker line and load terminals to said bus units.
 6. Mounting means as set forth in claim 5 in which said additional fastening means also includes an internally threaded insert in said mounting block means extending to a forward surface thereof, a bolt threadably received by said insert with a body portion of said bolt extending forward of said insert; said spring means being mounted to said body portion; adapter means interposed between said bus units and said mounting block means; said adapter means having an ear portion with an aperture through which the body portion of said bolt extends and said spring means biasing said ear portion toward said forward surface of said mounting block means. 